Glyceraldehyde-3-phosphate dehydrogenase is negatively regulated by ADP-ribosylation in the fungus Phycomyces blakesleeanus

Dormant spores of Phycomyces blakesleeanus contain a 37 kDa protein that is endogenously mono-ADP-ribosylated. This protein was purified and identifie d as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by N-terminal sequenc ing and homology analysis. GAPDH enzymic activity changed dramatically upon spore germination, being maximal at stages where ADP-ribosylation was near ly undetectable. The presence of glyceraldehyde 3-phosphate in this reactio n affected the [P-32]ADP-ribosylation of the GAPDH. ADP-ribosylation of the GAPDH occurred by transfer of the ADP-ribose moiety from NAD to an arginin e residue. A model for the regulation of GAPDH activity and its role in spo re germination in A blakesleeanus is proposed.